Tracer-guided reproducing machine



June 24, 1952 M. TuRcHAN TRACER-GUIDED REPRODUCING MACHINE 1l Sheets-Sheet l Filed Dec. 27, 1948 wm K @m E Nw N 1 M M ...4 M

June 24, 1952 M. ruRcHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Filed Dec. 27, 1948 l1 Sheets-Sheet 2 rromvex Bg. 2 Y

June 24, 1952 M. 'ruRcHAN TRAcER-GUIDED REPRODUCING MACHINE 11 Sheets-Sheet 5 Filed Dec. 27, 1948 INVENTOR. MANUEL TuRcHA lv.

1,/ ATroRNEK June 24, 1952 M. TuRcHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Filed Dec. 27, 194e 1'1 sheets-sheet 4 JNVENTOR. MAM/6L 7' URC/MN ATTO/MEX f IlI llll IN VEN TOR.

MANUEL ruRcHA N.

llslll TJ'ORNE K- June 24, 1952 M, TURCHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Filed Dec. 27, 1948 11 Sheets-Sheet 6 INVENTOR. ww/EL Tum/MM 1 `L .AfITToRA/Ey June 24, 1952 M, TURCHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Filed Dec. 27, 1948 11 Sheets-Sheet 7 INVENTOR. MANUEL TURCHA IV.

BY@ Y ATTGRNEK June 24, 1952 M, TURCHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Fnled Dec. 27, 1948 1l Sheets-Sheet 8 88 INVENToR. ANNUEL TURCHAN.

A TTORNE Y June 24, 1952 Filed Dec. 27, 1948 ll Sheets-Shea?l 9 1N VEN TOR. MANUE L TURCHAN.

l ATTORNEY,

June Z4P 1952 M. TURCHAN 2,601,345

Tamm-GUIDED REPRODUCING MACHINE Filed Dec. 27, 1948 11 Sheets-Sheet 10 Iig. /6

IN VUV TOR.

MANUEL TURCl-IAN.

Arran/VEZ June Z4, 1952 M, TURCHAN 2,601,345

TRACER-GUIDED REPRODUCING MACHINE Filed Deo. 27, 1948 1l Sheets--Shee'l ll IN1/Ewan. www@ MMM/QN.

M TT'RNE V Patented June 24, 1952 UNITED STATES PATENT OFFICE TRACER-GUIDED REPRODUCING MACHINE Manuel Turchan, Dearborn, Mich.

Application December 27, 1948, Serial No. 67,469

(Cl. Sit-14) 9 Claims. 1

My invention relates to a new and useful improvement in a tracer-guided reproducing machine adapted for reproducing on a work piece the form and shape of a pattern or master over which a tracer is adapted to travel. These types of machines are either mechanically operated, electrically operated, or hydraulically operated; and in the present invention I have indicated the machine as being hydraulically operated in part, but it will be obvious from the description that other means of operation may be resorted to instead of the hydraulic mechanism set out. In machines which are tracer-guided or tracercontrolled, diiiiculty is encountered in making an undercut, as in most types of tracer-operated machines, it is impossible to make an undercut where it is necessary to cut to the right and to the left, or to cut in and to cut out. It has also been experienced that while it is common to reproduce by cutting to the right or to the left, it is impossible to have a tracer-controlled machine operate, under conventional types of construction, in such a manner that it may cut, in reproducing on the work piece the form of the pattern or template, both to the right and to the left at the appropriate times. It is an object of the present invention to provide a reproducing machine in which such cutting may be effected.

It is another object of the invention to provide a plurality of slides on which the cutting tool is mounted and which may slide, selectively, at various angles relatively to each other.

It is another object of the present invention to provide in a working machine a traveling slide carrying a pair of slides movable relatively to the traveling slide and so arranged and constructed that one may move in a path of travel angularly to the traveling slide in the direction of its travel, and the other may move angularly to the slide in a direction opposed to the direction of movement.

It is another object of the present, invention to provide a plurality of slides so arranged and constructed that when one of the slides is moved, all of them are moved, and when some of the slidesare moved, some of the slides remain stationary, thus determining the resultant path of travel of the cutting tool which is carried on one of the slides. l

Another object of the invention is the provision in a machine of this type of a plurality of slides having hydraulic supporters or mechanism for moving the slides selectively and so arranged and constructed that the direction of movement may 2 be varied depending upon a position of a control valve.

Another object of the invention is the pro vision of a reproducing mechanism particularly adapted for mounting on machines having slidable carriages such as the carriage of a lathe, and provided with tool-carrying slides so arranged that the tool may be moved relatively to the carriage angularly in one direction and angularly in another direction selectively.

Other objects will appear hereinafter.

It is recognized that various modifications and changes may be made in the detail of structure illustrated without departing from the invention, and it is intended that such shall be embraced within the scope of the claims which form a part hereof.

Forming a part of this specification are drawings in which,

Fig. 1 is a fragmentary perspective view of a lathe, showing the invention applied,

Fig. 2 is a fragmentary top plan view of a lathe, showing the invention applied,

Fig. 3 is a diagrammatic view illustrating the invention,

Fig. 4 is a side elevational View of the view shown in Fig. 3,

Fig. 5 is an end elevational View of Fig. 4,

Fig. 6 is a diagrammatic view of the hydraulic circuit used in the invention,

Fig. 7 is a fragmentary sectional View taken on line 1--1 of Fig. 3,

Fig. 8 is a fragmentary sectional view taken on line 8-8 of Fig. 3,

Fig. 9 is a longitudinal central sectional view through the tracer mechanism used in the invention,

Fig. 10 is a diagrammatic view of the hydraulic circuit used in the invention with portions of the tracer valve and the changeover valve shown in section,

Fig. 11 is similar to Fig. l0, but with the valve element in the changeover valve rotated degrees from the position shown in Fig. 10.

Fig. 12 is a sectional view taken on line: l2-I2 of Fig. 3,

Fig.'13 is a fragmentary sectional view taken on line l3-I3 of Fig. 9.

Fig. 14 is a diagrammatic view similar to Fig. 10, but with a tracer valve in a different position,

Fig. 15 is a diagrammatic view similar to Fig. 11 and also similar to Fig. 14, but with `the changeover valve rotated 90 degrees clockwise,

Fig. 16 is a diagrammatic view similar to Fig.

3 14, but with the changeover valve rotated 180 degrees,

Fig. 17 is a diagrammatic View similar to Fig. 15, but with the changeover valve rotated 180 degrees.

Referring to the drawings, a lathe bed iii is shown in Fig. 1, upon which are positioned parallel spaced guideways 2|) adapted to slidably support the lathe carriage 2|. A suitable power-operated lead screw 22 is provided, which is arranged in threaded engagement with a suitable lead nut carried by the nut support 23, which depends from said carriage, being secured thereto by the nut 23a. Lead screw 22 is rotatable in one direction or the other and, being in threaded engagement with the lead nut, is adapted to effect reciprocal traversing movements of the carriage 2| on the guideways 24.

Lower cross-slide 24, Figs. 7 and 8, is slidably positioned upon the carriage 2| and is adapted to transverse adjustment thereon. The carriage 2| includes the dovetail 2e arranged transversely of its direction of feed movement, said dovetail cooperatively projecting within a corresponding dovetail recess formed on the under surface of the lower slide 24, a suitable gib 21 being interposed.

Transverse adjustment cf the lower slide 24 may be effected manually by manual rotation of the hand wheel 25, which effects rotation of the .lead Screw shaft 25a shown in Fig. l. Said lead screw is rotatably journaled through a portion of the carriage 2| and threadably engages ar feed nut carried by the lower slide 24, which is not shown but which operates in the conventional manner for permitting manual transverse adjustments of the lower slide 24 with respect to the carriage 2|.

Referring to Fig. 1, there is shown a conventional rotatable headstock 2 8 upon which is -positioned the work piece2i3. The bed I9 also carries a tailstock 3U at its opposite end, from which inwardly projects the support 3| for the tailstock center 32, which is employed when a Work piece is supported between headstock 28 and the tailstock 30. As shown in Fig. 1, however, the tailstock 30 is not employed as the work piece 29 is positioned entirely upon the headstock 28.

The upstanding bracket 33 is secured to carriage 2| for movement therewith, said bracket including a conduit and pipe connection for lubricating carriage 2|, the details of which will 'be described hereafter.

A suitable template support '34 is mounted upon the lathe' bed I9 upon the upstanding template supporting pillars 34a, one of which is shown in Fig. 1 at the left end of the template support 34. Template 35 is adjustably secured upon the template support 34 for engagement with the vtracer tip of the tracer mechanism in the manner hereafter described in detail.

The vcross-slide 24, as shown in Figs. 7 and 8, has, slidably and adjustably mounted thereon the angularly-arranged center slide 35, which in the present embodiment is positioned at an angle of 45 degrees to the longitudinal axis of the lower cross-slide 24. This slide 36, also shown in Fig. 3, is secured to the hydraulic cylinder V38 for movement therewith in the manner hereafter described. Piston 39 is positioned within the hydraulic cylinder 38, said piston having a piston rod 40 whose outer end is secured at 4| to the lower slide 24, as indicated in Fig. 8. Consequently, it appears that reciprocal movement of the hydraulic cylinder 38 with respect to the pis- 4 ton 39 will effect reciprocal movement of the center slide 36.

Angularly arranged dovetail 43 projects upwardly from lower slide 24 and extends within a correspondingly-shaped dovetail recess 43a formed within the lower surface of the center slide 3S, there being a suitable gib 43h interposed.

It will be noted that the dovetail 43 also extends in a direction at an angle to the longitudinal axis of lower slide Se, said angle in the present embodiment being preferably 45 degrees.

Referring again to Figs. 7 and 8, an angularly extending top slide 44 is slidably positioned upon the center slide .'t and is arranged at approximately a SiO-degree angle thereto. 1t follows further that the top slide 44 is arranged at an angle to the longitudinal axis of the cross-slide 24 which in the present embodiment is 45 degrees.

The top slide 44 has an extension upon the end of which is secured the hydraulic cylinder 45 for effecting reciprocal movement of the said top slide. Stationary piston 47 within cylinder 45 has a piston rod 43 which projects through the casing of the cylinder 45 and is secured at its outer end to the center slide 38 at the point 49. Consequently, reciprocal movements vof the cylinder 45 with respect to the piston 4'! will effect corresponding reciprocal movements of the top slide 44.

As shown in Fig. 8, there is Van upstanding dovetail projection 46 positioned within a correspondingly-shaped dovetail opening 46a, there being a suitable gib interposed. It follows that the top slide 44 is reciprocally slidable upon the center slide 36 in a direction at an angle to the longitudinal axis of the lower or cross-slide 24.

Referring to Figs. 3, 7, and 8, it will be seen that the lower cross-slide 24 is adapted for in- Aand-out adjustments transverse to the direction of movement of the carriage 2|, said adjustments being eiected by the hand wheel 25 shown in Fig. l. When so adjusted, either inwardly or outwardly, it will be seen that the center slide 36 as well as the top slide 44 will similarly be adjusted inwardly or outwardly. The center slide 35 is adapted to reciprocal movements at an angle to the direction of movement of the carriage 2| under the control of the hydraulic cylinder S8. When so adjusted it will be seen that not only is the slide 36 adjusted, but also the slide 44 which is mounted thereon. Top slide 44, as shown in Fig. 7, is also adapted to reciprocal movement under the control of `the hydraulic cylinder 45. However, it will be seen that reciprocal movement of the top slide will be separate and independent of the center slide 3B as well as the lower slide 24. Y

It is apparent from Figs. 1 and 3 that the two hydraulic cylinders 38 and 45 are arranged at an angle to each other which in the present embodiment is an vangle of degrees. This follows from the fact that each of the slides 36 and 44 respectively are arranged at acute angles to the longitudinal axis of the lower or cross-slide 24, which in the present embodiment is an angle of 45 -degrecs.

Carriage 2| is adapted for reciprocal movement in one direction or the other1 upon the guideways 20 under the control of the rotatable lead screw 22. The lower cross-slide 24 is adapted for transverse manual adjustment in and out under the control of the hand wheel 25. The center slide 36 is reciprocally mounted upon the lower slide 24 and is adapted to angular reciprocal movement on said lower slide under the control of the hydraulic cylinder 38. Furthermore, the top slide 44 is slidably positioned on the center slide 36 with its longitudinal axis arranged substantially at 90 degrees to the longitudinal axis of the slide 36. The top slide 44 is recprocally adjustable upon the slide 36 under the control of the hydraulic cylinder 45.

Referring to Figs. 1 and 3, top slide 44 is bifurcated and provided with guideways 52, upon which is slidably positioned the supporting plate which projects from the upright supporting bracket 56. The slide 5| has a recess 53 within which is secured the nut 54 in threaded engagement with the manually rotatable lead screw 55. Said lead screw has a shaft 56 with a hand wheel 51 at its outer end for effecting in-and-out adjustment of the tracer-supporting bracket 50-5|.

As shown in Fig. 1, the hand wheel 51 is positioned adjacent the left end of the top slide 44, there being a suitable formation therein for supporting the outer end of the lead screw shaft 56. The inner end of said shaft is journaled and supported within the bearing 58, which is secured within a corresponding recess 59 formed within top slide 44. Consequently, manual rotation in one direction or the other of the hand wheel 51 will effect corresponding in-and-out adjustments of the tracer bracket 58-5|.

As shown in Figs. 1 and 4, a suitable cover plate 60 is suitably secured upon the top slide 44 above and in spaced relation to the inwardly and outwardly adjustable slide 5|. This cover plate 68 has been removed from the plan view of Fig. 3 for clarity.

The upright tracer barrel 6| is positioned and secured within the bracket 5|] carried upon the top slide 44, within the upper end of which is secured the ball race 62 with the angularly inclined surfaces 65. There is a corresponding circular ball support 63 carrying the ball bearings 64 for cooperation with the ball race 52 and the inclined surfaces 65, the balls 64 engaging in a groove formed in the support 63. The upright tracer arm 66 is centrally positioned within the tracer barrel 6| and has secured thereto intermediate its ends the ball support 63, as shown in Fig. 9, with the upper end of the tracer arm 66 projecting upwardly and outwardly from said tracer barrel.

` A hollow cap 61 is suitably secured to the tracer arm 66 upon the outside of the tracer barrel 6|, said cap having an annular flange whose interior diameter is greater than the exterior diameter of barrel 6|, said flange projectingdownwardly around the upper end of said barrel.

The adjustable hollow presser ring 68 is threadably positioned Within the upper end of the tracer barrel 6|, its inner surface in cooperative engagement with the ball race 62, there being a suitable locking ring 69 provided for effectively securing element 68 vin the desired adjusted position.

It will be noted that the tracer arm 66 is secured to the ball support 63 for movement in unison with the balls 64 carried by support 63 adapted for cooperative engagement with the inclined surface 65 on the ball race 62.

A central longitudinal slot 18 is provided within the upper end of the tracer arm 66 and is adapted to receive the adapter 1|a, within which is positioned tracer `tip 1|. A knurled nut 12 has a central opening through which the tracer 6 tip 1| extends, said nut being threadably engaged with the outer end of the tracer arm 66 to effectively secure the adapter 1|@ within the end of said tracer arm. A suitable transverse slot 13 is provided adjacent the outer endl of the tracer arm 66 giving access to the slot 10 Within said tracer arm to facilitate removal of the tracer tip supporting adapter 1|a.

As shown in Fig. 9, a semi-spherical opening 14 is formed centrally within the lower end of the tracer arm 66 for cooperatively receiving the spherical ball 16, said ball extending within a conically-shaped opening 11 in the control valve 18 whereby any transverse or axial movement of the tracer tip 1| will be transmitted to the control valve 18 to function in the manner hereinafter set out.

As shown in Fig. 1, the tracer tip 1| is adapted to engage the surface of the template 35, said tracer tip from time to time receiving lateral thrusts, which lateral thrusts are transmitted to the tracer arm 66 and to the balls 64. A lateral pressure exerted upon the tracer tip 1| has a tendency to cause the balls 64 carried by the tracer arm to ride downwardly on the inclined surfaces 65, with the result that the tracer arm 66 will move downwardly in a direction substantially parallel to the longitudinal axis of the tracer barrel 6|, which movement of the tracer arm 66 is adapted through the ball 16 to effect downward movement of the control valve 18 controlling the flow of pressure fluid.

The control valve 18 has formed in its outer cylindrical surface the three annular openings 8|, 62, and 83.

The sleeve 84, which slidably receives control valve 18, has an annular ange at its upper end which extends into and threadably engages with the lower end of the tracer barrel 6|. said sleeve having a plurality of fluid passages 85, B6, 81, 88, 89, and 96 formed therein.

As shown in Fig. 9, the drain conduit 9| is joined to the tracer valve housing |06, which has a suitable passage therein establishing communication between the drain conduit 9| and the passage formed within the valve sleeve 84.

As the control valve 18 is slidably positioned within the valve sleeve 84, it follows that there will be some oil seepage gravitating downwardly and collecting within the annular chamber 91. In View of the connection between the chamber 91 and the drain 9| by means of the passage 90, it is clear that this oil is withdrawn from the tracer housing as it collects within the collecting chamber 91.

Referring to Fig. 6, a hydraulic power unit is diagrammatically indicated as element |28, said unit including a suitable fluid storage sump as Well as a hydraulic pump in communication therewith for supplying pressure fluid to the fluid delivery pipe 92. This delivery pipe: 92 extends from the hydraulic unit |28 and is joined at its other end to the tracer housing |66. There is also an exhaust conduit 93 to connect the tracer housing |06 and the hydraulicunit |28 for transmitting exhaust fluid from the cylinders back to the fluid storage sump within the said hydraulic unit. As shown in Fig. 9, the fluid pressure delivery conduit 92 is joined to the passage 8s by the intermediate passage 92a indicated by dotted lines inthe drawing. It will be seen that pressure fluid supplied from the conduit 92 is thus directed to the passage 88 and, depending upon the positioning of the control valve 18, will be `transmeenam mittedto either of the cylinder supply passages 81 or 89'.. whchrespectively communicatewith passages' ||.8' and; |'l'9r shownin; dotted lines in, Eig.; 9 and being arranged within the tracer housing |06..

Referring to Fig.A 6; it is seen that there is a pair of conduits |2| and |22 which join the tracer housing |06, said conduits being respecr tively joinedto the? passages H8 and l: |191 within thev tracerI housing |106.) (Fig. 9).

Again referring to Fig. 9, a suitablev cover 9.4 threadably extends. within tracer housing |06 to form a closure for the lower end. thereof. A suitable bearing .95 is positioned within the lower endof` the-.cap 94 adjacent the central upright; annular ange. 9B, which has a central opening to slidably receive the valve stem 98.. Sai-d'` hollow'upright projection 96 performsthe further function ofpreventing any oil seepagel which collects within the: chamber 91 from. escaping down the. stem 98, saidelement 96 cooperating with the chamber 91.' to provide av` closurev for retaining this seepage.

Valve stem 98, secured atv its upper end to the iiu-idj control valve 1,8.. slidably' extendsV through thehollow sleeve formation SB and' projects belowcap 94: of. theV tracer housing |06. 99=is positioned adjacent the lower endk of the valve lstern 98 andis secured thereon. by the nut |-00,' as shown.. Y

Thev transverse slot |02' formed. with-in" the tracer arm |56V intermediate its ends and, within the. tracerbarrel (it isl adapted to slidably' refceive the transverse stabilizer' pinl |03;l which is eccentrically mounted at |04 at itsI ends within the spaced ball bearings lsecuredwithin the tracerv barrel 6 The stabilizer pin |03 is intended. tol slidably i-'egulatev the vertical reciprocaly movements of the tracer arm` 66, at the sano@ timeY preventing rotation thereof.

A coil springlilll extends around the' upright projection E36-which iorms"apart of. the cap 94 witlr its opposite ends interposed between bearing-95 `carried in thefcapl 94 and the lower-l end ofthe-control valve- T8. Consequently, it is. apparentr that the control valvev is: supported. upon thelcoilspring |91--r andis thus in a floating condition within the valve sleeve 04T. The initial positioning of the controlvalve-'|8- withinfs-aid sleeve may be controlled by" manual ad-iustment.

of. the cap 94 regulating the' tension within the coil spring` |04.. Thus, it is seen that.l upward movement -of' the control valve 'lf3 -is effected by the coil spring ||l|,4 whereas lateral pressure upon the tracer tip 1| operating through the tracer arm B6 controls the downward movement ofthe control valve 18 against the tension of the spring |I.

W The 'trace-r barrel 6|- is supported in an upright position within an opening in the bracket150 and isv adjustably secured in position by the-removable plate |01 secured thereto bythe screws |08.

Still referringto Fig. 5, there is aV pivotal arm |09 pivoted at to the-lower end of the Vtracer valve housing. |:06,. one end of said arm ||0 being bifurcated at |09 to. cooperatively receive a portion of the disc 99.011.-=thevalvev stem 98. The opposite end of the lin-k;A |109 is pivotally joined at ||2v to the vertically@movable` control shaft H3.

Said shaft projects upwardly into the house ing ||4 and carries at. its upper end thecircular disc ||5 in cooperative engagement with the manually rotatablek cam H9.

As viewed in Fig. 4, itvwillbe's'een thatV the Disc housing H4 is secured to and carried bythe control valve housing |06 by the screws; Hic; Themanually rotatable shaft which carries the cam H6, extends from the housing llband has at its outer end the: manually ope-rated handle H9; A suitable coil spring |I8 is positioned-Y within the housing lll-interposedfbetween. the lower end thereof and the under surface of the disc ||5 upon the control shaft ||3. By this construction,v it isk apparentithat manual rotation. in one direction or the other of the handle ||9 will effect a corresponding. rotary move-v ment` of the cam H6; said cam in turn. will cause downward movement of the. controlfarm H3 against the action of. the spring H8, and

this Ydownward movement in turn will effect pivotalmovement` of the link |09 to cai1se-up-l ward. movement of the valve stem 9.8. It-.fol-KA lows that moving the handle ||9 in the oppositedirecti-on will cause or permit the control arm H3 tof be moved. upwardly under the. action-.vof the spring I9, andin that case the link |09 will be.- pivoted in a clockwise direction, causing dow-n..-V ward movement of they valve stem 99.. Thus', there is shown in Figs. 4 and 5 a: manual controlfor the control valve-'i8 within the.- tracer housing` |99. Thsmanual control isrused; primarily in setting up the tracery mechanismand securingzrits,v proper relationship with the pattern beforethe machining operation. This manual control.V is also usefulfor controlling movement ofthe cylinder under tracer control at the endr of, the turning operation.

Now referring tov lig.` 6', itis seen. thatJ the two conduits |2| and |22 which project from the tracer valve housing |06 are joined to: the. changeover valve |123.. there being .a shut-offvalve |24 interposed in the-line- |2|A and controlled by the arrn |25. Depending uponthe operationof the tracer valve.V within; the tracer housing.. |06, either of the lines |2| or |22l will conduct-pres?- surefuidto one end or` the other of either of the two cylinders 3901' 45', depending u-pon. ther posi.- tioning ofthe rotatablevalve elementwithin the changeover valve.Y |231. It. follows further that either of the other of the twocondu-itslll or LZ2-l will conduct exhaust uid back fromvthe cylinder under'tracer control back tothe tracer housing and thence back to the hydraulic unit throughI the.A exhaust4 line 93'. Y

As shown in Fig. 5, the, conduit. |L2`| is` joined to the changeover valveY |23 at the pointY |I26`, whereas. theconduit. |224 is joined to saidichange.-

valve at. the. point |21.-

Referring nowV to. Fig. 10, which a. diagram;- inatic. view illustrating the. various pipe. connec tions'betweenthey hydraulic unitj |120' and. the. tracer valve sleeve 84 as well as the connections between. the tracer valve sleeve 84 and the' changeover valve housing |23. Thef changeover valve. is shown in. sectionfor clarity; There are. also shown` two hydraulic. cylinders. 38' and 45 with. various ppes.- connecting the respective opposite ends. of. said cylinders-andjoutletports of the changeover valve |23.

There is a. plurality of outlet ports L28. |29',r |39, and |.3|. spacedrelation. formed within theV changeover valve housing.v |23.; The conduit |32 interconnects. the outlet portl`2l8 and one end of the hydraulic: cylinder 45'.v A. conduit |33', interconnects the opposite. end. of' the cylinder 45' andthe outlet port L29. The conduit. |34 interconnects the.- outlet port. |30 and. one. end. ofthev `ends of one of the two cylinders 30 or 45.

9 port |3| in the changeover valve housing |23. Thus the outlet ports |28, |29, |30, and |3| are respectively joined by the conduits |32, |33, |34, and |35 with the opposite ends of the hydraulic cylinders 45 and 38.

There is a manually rotatable valve element |36 positioned within the changeover valve housing |23, said valve element being rotated to the desired position in the manner hereinafter explained by the control arm |31, which is suitably joined to the rotatable valve element |36 and which is positioned on the outside of the changeover valve housing |23.

As previously described, a supply conduit |2| is joined to the fluid opening |26 in the changeover valve, and at the same time the other conduit |22 is joined to the fluid opening |21 therein. Depending upon the positioning of the valve element within the tracer valve housing, that is, within the valve sleeve, one of the two conduits |2| or |22 will be delivering pressure fluid to the changeover valve housing, and the other will be conducting exhaust uid therefrom back to the tracer housing for subsequent exhausting to the hydraulic unit and the sump therein. In Fig. 10, it will be assumed that the tracer control valve 18 is moved to the position shown so that pressure fluid from the hydraulic unit will be supplied to the changeover valve through the conduit |2|, and in that case the other conduit |22 will be conducting exhaust uid from the changeover valve to the tracer valve housing.

The rotatable valve element |36 within the changeover valve |23 has a plurality of spaced annular openings |38, |39-, |40, and |4|, which are shown in the sectional portion of Fig. 10, adapted for communication with the fluid ports |28, |29, |30, and |3| respectively.

There are four parallel spaced, non-communieating channels of varying length arranged within the valve element |36, any two of which, depending upon the positioning of the valve element |36 within housing |23, are adapted to establish lcommunication between the opposite As shown in Fig. 10, there is a long passage |42 in communication at its upper end with the annular opening |33, whereas its lower end is in communication with the fluid inlet port |43. From the initial assumption that pressure fluid is being supplied through the conduit |2|, it will appear that said pressure fluid will be delivered to the opening |26 for communication through the changeover valve housing |23 to the inlet opening |43, and then through the long conduit |42 to the annular opening |38, through the housing |23 to the cylinder port |28, and thence through the conduit |32 to the outer end of the hydraulic cylinder 45.

A second inlet opening |44 is shown at the lower end of the rotatable valve element |36 opposite from the inlet port |43. It will be seen from the drawing in Fig. l that said inlet port |44 is in communication with the opening |21 in housing |23, and this in turn communicates with the fluid exhaust pipe |22. There is a second upright passage |45 arranged in spaced relation from the passage |42 with its upper end in communication with the annular opening |39 `and its lower end in communication with the port |44. It will be noted, and as above described, the annular opening |39 is connected with the cylinder port |29 and through the conduit |33 joins the inner end of the hydraulic cylinder 45. This represents one positioning of the valve element 36 within changeover valve |23, and as above described, pressure fluid is being supplied through the pipe |32 to the outer end of 45. Exhaust fluid from cylinderv 45 is being returned through the conduit |33 back to the cylinder port |29, and through the passage |45, port |21 and the conduit |22, back to the tracer valve sleeve 84, thence exhausted back'to the hydraulic unit |20. i

It will be apparent if we continue with the assumption that pressure fluid is being supplied through the pipe |2|, that the rotatable valve element |36 may be rotated 180 degrees from the position shown in Fig. 10. In this case, port |44 will be in communication `with the port |26, with the result that the pressure fluid supplied from pipe |2| will be conducted through port |26, opening |44, passage |45, annular opening |39, cylinder port |219, and conduit |33, to the opposite end of the hydraulic cylinder 45; and it will be noted that when the rotatable valve element |36 is rotated 180 degrees'from the position shown in Fig. l0, that the pressure fluid supply is reversed from one end of said hydraulic cylinder to the other, and likewise the exhausts connected to said cylinder have been reversed. From the above description, it is apparent that the cylinder 45 is the only cylinder that is vunder tracer control, and that the cylinder 38, in view of its connection withthe changeover Valve, is receiving no fluid and is entirely inactive.

Referring to Fig. 11, the changeover Valve |23 is, however, adapted for changing the fluid pressure connections in such a fashion that tracer controlled iiuid will be supplied and exhausted to one end or the other of the hydraulic cylinder 38. As shown in Fig. 1l, the rotatable valve `element |36 has an additional two' iiuid inlet or exhaust ports |46 and'l41, and when therotatable valve element |36 is rotated -90 degrees from position shown in Fig. l0, the port |46 will be in communication with the port |26 of the changeover valve housing. Continuing with the original assumption that pressure uid is being supplied through the conduit |21, it should follow that said pressure fluid will then be made available through the port |26 to the opening |46 at the lower end of the rotatable valve element |36. A third spaced channel |48v is found within the rotatable valve element |36 in` spaced relation to the other two channels |42 and |45. The upper end of the channel |48 is in communication with the annular opening |40, whereas the lower end lof the channel |48 is in communication with the inlet or exhaust port |46. A fourth channel |49 in parallel spaced relation to the other three channels |42, |45, and |48 is also formed within the rotatable valve element` 36, the upper end of the passage |49 being in communication with the annular opening |4|. The lower end of the passage |49V is in communication with the fluid inlet or exhaust opening |41 formed within the lower end of the rotatable valve element |36.

Consequently, as shown in Fig. 11, the valve element |36 has been rotated 90 degrees from the position shown in Fig. 10, and pressure fluid through the conduit |2| is being supplied through the passage |48 to the annular opening |40 and thence to the cylinder port |30. From cylinder port |36, the pressure fluid is conducted through the pipe |34 to the outer end of the hydraulic cylinder 38. At the same time, exhaust fluid |35 into the cylinder port. |3|. There is shown 1l :inFig 11 the :exhaust iiuid .ilowing into .the opening :14.1 :and through the `passage 149, thenceV `.the port 1.41., and returning to the tracer valve .through the conduit 122. Consequently, from theposition of the valve element .shown in 'Fig. .11,pressure :fluid-from the pipe 121 is conducted -through the channel 143 to the outer end of `the hydraulic Ycylinder .38. .At the saine time, exhaust fluid from said cylinder returns to the changeover valve and through Athe passage 149 returns to '..the tracer valve through the pipe 122. It will be apparent also .that connections to the opposite ends .ofthe cylinder '38 may he reversed by rotating the .rotatable .valveelement 136 `lilrdegrees from the position shown in Fig. 11. In this case., it Vwill .be apparent that a pressure .fluid.suppliedpthrough vthe pipe 121 Vwill be .delivered through the shortv channel mi) to the Ainner end of `the hydraulic vcylinder 38, .and exfhaust from the opposite end of said cylinder will bereturned through pipe `1.34 and through passage Hfand :thence through the pipe 148, open- :zing 1346. and opening .12"1, pack to the tracer valve Y.thm-ugh the pipe 122.

.From an examination of Figs. and 11, it

.appears that tracer .controlled nuid from the ltracerfvalve is :supplied through either lof the pipes 1.2.1 or 1.2.2,V depending uponthe positioning of .the valve element Within the tracer in vresponse `to vthe tracer tip engaging the surface of the pattern, so thatpressure fluid is supplied V.through the pipes 1.2.11 or 122 to the changeover valve Vhousing 123. Said changeover valve has :av'fpair of inlet openings 126 and V121 conducting Vpressure:fluid.from either of `the pipes 122 or 121.110 the interior of -the'changeover valve. The manuallyrotatable valve element 136 within the y1.2hangeover valve :has four inlet openings 143,l 144, "1:46, and 141 .formed therein :andzspaced :at

,901degrees Afrom each other. 11n the positionof vthe rotatable valve element v13B in Figglo, only theinlet yopenings `143 and 14.4 `are effective., said @openings .being respectively .in communication with theinletorf. exhaust openings 126 and 1271. 'It is only when the rotatable valveelement 136 .is rotated 9 0 degrees to the position shown in Fig. ll, that .the second two oppositely arranged Yports -Mand 141 are .in communication with the :openings 126 and 121.. Thus it is apparent that tracer control may be changed from one .cylinder to the other.

`Still :referring to Figs. 1i) and 11, it will be re- -membered that .the initial assumption taken in connection with the description .of said figures contemplated that .pressure fluid Was delivered from the tracer valve sleeve P84 to the conduit |21, whereas the-other conduit .122 back to theztracer sleeve conducted lexhaust iluid .from the change- :over valve. Referring more particularly to Fig.

l0, and in view ofthe above description, it is .apparent .that with the setting of the rotatable valve element :131i within the changeover valve Ylll, as shown in Fig. l0., only the hydraulic cylinder 45 Will be under tracer control.

Whether vpressure fluid will be supplied through the Atracer tip '111 against', the surface of the template, then it is apparent that a negative displacement or the tracer ytip as Where the tracer :engages a-depression Tin the template Will cause a movement of the tracer valve '118 in the opposite directiozr'so .that pressure iluid from the pipe line $2 from VVthe hydraulic unit 121] is transmitted :out from the tracer valve sleeve 84 to the pipe 122 and thence to the changeover valve at the inlet port 121. Fromtheabove description, it follows that exhaust .fluid from cylinder 45 will be returned to the changeover valve and Will return to the tracer valve through the exhaust pipe 121 .for subsequent exhausting through the .pipe "93 back to the hydraulic unitlIZ. In this case,.if there is a negative displacement or such :displacement as causes pressure uid to :be supplied throughthe pipe 122, it vthen follows that the pressure iluid will be supplied again tothe hydraulic cylinder 45, as there has vbeen no change in the rotatable valve element 136. ,However, pressure fluid will be supplied to the opposite end of the hydraulic cylinder45. As originally described and as viewed in Fig. 10, the pressure fluid was .supplied through the pipe |21; said pressure was delivered to the outer end of cylinder .45 through the conduit 132. It .conse- `fluently follows that With the valve changed to 'a different position so that pressure fluid issupplied through the pipe 122, then such pressure fluid will be delivered to the inner end of zthe cylinder 45 through the conduit 32.

' From the above description, it is clear `that with the changeover valve element 1.315 set 'In a particularposition, the tracer is capable of regulating the reciprocal movement of one of the cylinders such as the cylinder 4:5 described. Movement of the tracer valve in one direction will supply pressure fluid to one end of the cylinder for moving it in one direction, and furthermore, movement of the tracer valvein a different direction `will cause vpressure uid to be supplied to .the opposite end of .said cylinder for causing movement of said cylinder in the opposite direction.

-It also'fo'llovvs from the previous description of Fig. ll, Where the original assumption statedthat vpressure fluid Was supplied through the pipe 11:2'1 and Was conducted through the changeover valve Vto the outer end of the hydraulic cylinder 38, that if the tracer valve is moved to a diiTerent position from the position shown in'Fig. 11, that is,

a position to the left of what would be the central or neutral position of the tracer valve, in that case pressure fluid 'will be supplied .through the pipe 122 and exhaust Will return through the pipe 1251. Therefore, it would follow that Isuch `pressure fluid so supplied throughthe pipe 122 would he delivered to the inner end of the hydraulic cylinder '3S Y irough Vthe pipe 13'5 `and exhaust fluid from said cylinder would return through the pipe 134 through the changeover valve and return to the tracer housing through the pipe 121.

Consequently, in Fig. ll it is also true that here the cylinder 38 is under tracer control and cyllinder 45 is inactive. Furthermore, depending upon theV movements of the control valve within the tracer, pressure fluid Will be supplied through either of the pipes 21 or 122. Consequently, reciprocal movement of the hydraulic .cylinder 33 can be effected.

By virtue of -the construction of the changeover valve as set out in detail and the various pipe lconnections Vbetween said changeover valve and the tracer, it is quite clear that at no time can more than one cylinder be under tracer control.. et that time, when one cylinder is under tracer control, the other cylinder is entirely .inactive,

Referring to Figs. 10 and 11, as well as Fig. 1, itis contemplated during a reproducing operation where the tracer engages the surface of the template 35, that the carriage 2| will be fed continuously in one direction or the other along the Ways 20. Feed movement of the carriage 2| is effected by the rotatable screw 22, which is indicated in Fig. 1. It is contemplated also that the carriage 2| may be moved along the ways 28 under hydraulic power. Lubrication may be supplied to carriage 2| through the pipe |53 shown in Fig. 1, there being a suitable hand valve 5| interposed in said pipe for controlling the flow of lubricant therethrough. The pipe |58 is joined to and in communication `with the lubricant pipe |52 which is formed within the upright bracket 33 shown in Fig. 1.

Said bracket is secured to the extension 33a which forms a part of and is joined to the carriage 2|.

Whether the carriage 2| (Fig. 1,) is moved mechanically by the screw 22 or hydraulically makes little difference. It is contemplated that either of the cylinders 38 or 45 will operate simultaneously with the movement of the carriage 2| as it is fed along the ways 20 with movements of either of the cylinders 38 or 45 being controlled by the tracer.

The cross-slide 24 as indicated in Fig. 1 is operated manually by the hand wheel 25 and the shaft 25a. However, it is contemplated that the shaft 25a could be rotated mechanically or be power-driven. Whether the cross-slide is controlled or moved manually or under power, it is quite apparent that either of the two cylinders 38 or 45 may be operating under tracer control throughout feed movement of and simultaneous with the feed movement of the cross-slide 24. Thus, either cylinder may operate simultaneously with the movement of the cross-slide with either of such cylinders being under tracer control. Normally, when the cross-slide is being moved manually by the hand wheel 25 or by another suitable power means, the carriage 2| would be stationary.

In operation, moving from right to left of Fig. 1, the cutter |53 (not visible) may be said to be operating upon the front side of the Work piece 29. The opposite side of the work piece may be termed the back side. Of the two cylinders 38 and 45 which may be termed hydraulic motors, it would appear that the cylinder 38 would be used for cutting the front side of the work piece, and the cylinder 45 would be employed for cutting the back side of' the work piece or the back side of an under-cut. Consequently, it is possible by the present invention to reproduce over 360 degrees of the surface of the template in a particular Work piece. The changeover valve |23 is adapted to determine which of the two cylinders will be under tracer control, and thereafter the tracer mechanism is so connected as to effect reciprocal movement of the particular cylinder which is to be controlled.

Fig. of the drawings is a diagram of the pipe connections between the two cylinders 38 and 45 and the changeover valve |23 as well as the tracer valve 84. The movable valve element 18 which forms a part of the tracer is moved to the right from the neutral position of said valve element as shown in Fig. 9. This may be regarded as the position it would assume when the tracer is under a positive deflection, for example.

In Fig. 9 the tracer valve 18 is in a neutral position so that pressure fluid available through 14 the pipe 92 from the hydraulic unit |20 is completely stopped and there is no 110W of fluid through the tracer, as the position of the valve element 18 is such that passage 88 is completely blocked off.

Referring again to Fig. 10, it appears that tracer valve 18 has been moved to the position shown, which may be assumed to be a positive position, so that pressure fluid from the pipe 92 will flow through the passage 8l entering annular opening 82 so that fluid is now conducted 'to the outlet passage 88 and thence to the delivery pipe |2|. As :above described in detail, this pressure uid is available to the outer end of cylinder 45 through the conduit |32.

As shown in Fig. 1l, it will be seen that the tracer valve 18 is in the same position as in Fig. 10, so that pressure fluid is again supplied to the delivery pipe |2| for conduction to the change-Y over valve |23. However, it will be noted the rotatable element |36 within the changeover valve has been rotated 90 degrees from the position shown in Fig. 10 so that the tracer-controlled uid is now delivered to cylinder 38 into the outer end thereof through the conduit |34 in the manner hereinbefore fully described. i

Referring to Fig. 14, which is substantially similar to Fig. 10 with the exception that the tracer-controlled valve 'I8 has been moved in the opposite direction from the neutral position shown in Fig. 9, and this would correspond to the negative position of the tracer, which has before been described. Furthermore, Fig. 14 differs slightly from the diagram shown in Fig. 10 inasmuch as for purposes of illustration there has been taken a transverse section of the changeover valve |23, whereas in Fig. 10 there was a longitudinal section thereof. However, it is apparent that the rotatable valve element |36 is in the same position with respect to its housing |23 in both of the Figures 10 and 14.

Referring to Figs. 10 and 14, as the tracer control valve 18 has been moved to the negative position shown, pressure fluid will be delivered through the pipe |22 now, instead of the pipe 2 l, conducting pressure fluid to the port |21 of the changeover valve. This pressure fluid is then delivered to the opposite end of the cylinder 45, i. e., the outer end, through the conduit |33.

In comparing Figs. 10 and 14, it is apparent that when the rotatable valve element |36 Within the changeover valve remains unchanged, the movement of the tracer valve 18 to a positive position will conduct pressure fluid to the inner end of cylinder 45 through the conduit |32, whereas, and as shown in Fig. 14, when the tracer has assumed a negative position, pressure fluid will be delivered to the opposite end of cylinder 45 through the conduit |33. This means that for any given position of the rotatable valve element within the changeover valve, the tracer valve itself. depending upon its positioning, will regulate the reciprocal movement of one hydraulic cylinder such as the cylinder 45 above described.

In comparing Fig. 15 with Fig. 11, it is apparent that Fig. 15 is also a diagram of the various connectionsbetweenthe cylinders and the changeover valve as well as between the tracer. However, here also the rotatable valve element |36 is in the same position in both gures. Fig. 1,5, however, shows a transverse section of the changeover valve as contrasted with the longitudinal section thereof shown in Fig. 11 for illustration. Consequently, with the rotatable valve element |36 within the changeover valve in the same position,and with the tracer .control valve -18 vin 4the same position in Fig. l5 as in Fig. .11, itis clear that pressure vfluid should be delivered 'in both instances to the outer ends of the cylinder 38 through the pipes |341, the exhaust returning from :saidcylinder through the conduits |35.

Fig. vl5 may also vbe compared with Fig. 14, wherein Zit is seen that in Fig. 15 the rotatable valve element has been rotated .90 degrees in a clockwise direction. This means that the tracer control which in Fig. 14 was Vto one end of the hydraulic cylinder 415 changed over to one end of the hydraulic cylinder y38.

Fig. 16 inthe drawings is also a diagrammatic illustration of thevarious connections between 'the cylinder, the changeover valve, and the tracer, and it isseenin comparing Figs. 1.4 .and 16 that the tracer control valve element 18 is in a negative position and is to .the left of the central, neutral .position shown in Fig. 9, so that pressure "fluid supplied to the changeover valve through the conduit |22, with exhaust fluid returning fromthe changeover valve to the tracer through 4the .conduit .|2|, in the manner fully described hereinabove. In comparing Figs. le and 16, it is clear that the tracer valve 18 is in the same position with respect to the valve sleeve in both of these igures. However, it appears that the rotatable valve elementl within the changeover valve has Ybeen rotated in Fig. 16 180 degrees from the position shown in Fig. 14, Awith the result that 'the tracer control remains in the cylinder 145 but 'the negative positioning of the tracer control valve 18 in Fig. 16 causes pressure fluid to be supplied to the opposite end of the cylinder rom'that .shown in Fig. 14. In other words, the 4eleot of the negative positioning of the tracer 'valveelement 18 upon a particular cylinder connected thereto may be reversed at any time by rota-ting the rotatable valve element '|35 180 degrees from one position to the other. For example, tracing over Vthe surface of a pattern on Xone .side thereof, a negative positioning of the tracer arm will cause a particular cylinder to move in .one direction, carrying the tracer and :cutter vtoward the pattern and work piece respectively. Now, assuming it is desired to trace .the .opposite side of the pattern using the same arrangement of elements and there is also a negative deection it will be seen that in order that the tracer and cutter move toward the pattern `and work piece respectively, it will be necessary `for-the cylinder under tracer control to move in the opposite direction. Consequently, by being .able torotate the rotatable valve element |36 180 -degrees from one position to another, the control effect of the tracer valve 18 is reversed so that the negative positioning of the valve in one position'of the changeover valve causes the cylinder to move in one direction, whereas when the .changeover valve is rotated 180 degrees, the same negative positioning of the tracer valve will cause the cylinder under tracer control to move in the oppositedirection. Consequently, it is possible to trace over '360 degrees of a template or pattern.

Referring to Fig. 17, it is seen that this figure, which'is a .diagrammatic view of the connections between the cylinders, the changeover valve, and .the tracer, is substantially similar to the diagrammatic view shown in Fig. 15. It will be noted lthat the valve element 18 is in the saine positive position .in Fig. 1'7 as in Fig. 15. However, the rotatable valve element |36 inthe changeover valve has .beenrotated .in Fig. 17 180 degrees from kthe position -shownin Fig. .15.

ma'rns within the cylinder 38; however, the operative eiTect of the tracer control valve 18 is reversed and pressure iluid is now supplied to the opposite end of cylinder 38 through the conduit |35. From this it .follows that at any time no more than one of the two cylinders 38 or 45 is under tracer control. With one particular position of the changeover valve, the tracer will control iiuid depending upon the movement of the valve element 18 to either one end or the other of the cylinder under tracer control, with the other cylinder being inactive. Now, if .the changeover valve is rotated 90 degrees from a particular position, it will be seen that, as fully explained, tracer Acontrol will be switched from one cylinder to the other, the second cylinder now being under tracer control and with the flow being to one end or the other thereof depending upon the positioning of the tracer control valve element 13, with the rst cylinder now inactive.

At any time, however, when the changeover valve is rotated 180 degrees from one position to another, tracer control will remain in the particular cylinder under control; however, the effect of the movement of the tracer control valve 1B is reversed as far as the ow of fluid to a particular cylinder is concerned; that is,.if the `tracer in both cases is in a positive positioning, changing the changeover valve 180 degrees will cause a Y particular cylinder to move in one direction,

f retainingly positioned within the T-slot which is the opposite from the initial direction controlled by the positive positioning of the tracer control valve. In other words, when you rotate degrees, you do not change the control from one cylinder to the other; the control stays in the same cylinder, but the operative effect of the control valve is reversed.

Referring to Fig. 1, means are provided for supporting adjustably the tool holders carried by the top slide 44. More particularly, a pair of parallel guidewaysy its are arranged upon the top slide 4t, preferably in a direction parallel to the path of movement of the carriage 2|, there being an inverted T slot |55 between said guideways. Tool holder plate 15e is adjustably and slidably mounted upon the ways |54 and carries the block standard |51 upon which is mounted the tool hold-down plate |58.

1t will be seen from Fig. l and Fig. 2 that a plurality of cutting tools |53 may be mounted upon the tool holder plate |513 and retained between said plate and the tool hold-down plate |58. The latter is immovably secured to the block |51 by the plurality of set screws or bolts l 63 which threadably extend down through plate |58 and into corresponding threaded openings in the block |51 to thereby immovably hold the cutter blades |53 within the tool holder proper.

The tool holder is swivel mounted upon the guideways |55 upon the T-bolt |59, which is |55 and which extends upwardly through corresponding openings in the plates |56, |51, and |58. The T-bolt |59 extends upwardly beyond the top of the plate |53, and a cylindricallyshaped hold-down cap li! is positioned upon said bolt with its lower surface bearing .upon the top of the plate |58.

the intended work piece.

Manually rotatable locking arm |6| `is threadably-journaled upon the upper end of T-bolt |59 with its under surface operatively bearing upon the top surface of the cylindrical hold-down element |66 whereby once the `tool holder is swiveled to the proper position, the cutting tool |53 or the particular cutting tool employed with respect to the work piece 29 will be properly positioned and secured against rotary movement about the T-bolt |59.

The top nut |62 is threadably positioned upon the upper end of the T-bolt |59 and is adapted to retain the locking arm |6| on said bolt.

For various types of cutting operations and particularly in under-cutting, it is often necessary to change the cutting tool |53 for one of aslightly different shape in order to thereby negotiate certainvariations in the curvature of This may be accomplished merely by loosening some of the said screws |63 so that the particular cutting tool previously employed may be removed and another cutting tool of the proper shape inserted and secured. On the other hand, a plurality of `diiTerent-shaped cutting tools |53 may be positioned upon the tool compound and the desired cutting tool may be rotated into proper position merely by loosening the locking arm I6 Thereafter the same is tightened again and the compound is immovably retained in the proper position for the cutting operation.

`Referring to Fig. 2, the work piece to be reproduced from the template 35 when finished includes a plurality of surfaces |64, |65, |66, |61,

|63, |69, and |19.

In the formation of these various surfaces by' the particular cutter employed, it is contemplated as part of the present invention that either of the cylinders 38 or 45 will be employed for a portion of the cutting operation depending upon the positioning of the particular surface to be cut. For example, reproducing the surfaces |64 and` |65, the changeover valve |23 will be adjusted through rotation of its rotatable valve element |36 so that the tracer control will be in the cylinder 38 solely and the reproduction by the cutter will be along the line 38a indicated in Fig. 2 with respect to the work piece 29. It will be noted that throughout the cutting operation the carriage 2| is beingcontinuously fed along lines parallel to the axis of the rotatable work piece. Naturally the present invention contemplates cutting devices where the work piece is stationary and the carriage 2| is movable in a predetermined plane. At any time while the cutter is negotiating the surface |65 and prior `to going over the surface |66, it will be desirable to soA adjust the changeover valve to switch tracer control from cylinder 38 to cylinder 45, and the feed movement to correspond to the arrow indicated at 45a corresponding to the feed movement of the cylinder 45.` It follows, therefore, that for the balance of the cutting upon the surface |65, tracer control will be to the cylinder 45 and will continue as the cutter begins to move into the portion of the workpiece designated by the numeral |66 and thereafter the surface |61 or a portionthereof.

At an intermediate portion of the surface |61, it is quite apparent that it is desirable to now switch back tracer control to the cylinder 38. This is done by again adjusting the changeover valve to the initial position so that the cutter is moving at an angle indicated `by the arrow 38a, continually negotiating the surface |61 as well as thesurfaces` |68 and |69.

Midway or, for that-matter, at any point along the surface |69, it will then be desirable to switch tracer control to the cylinder 45, and this is done by again adjusting the changeover valve to the second position above recited, with the tracer now controlling cylinder 45. The direction of feed movement of the cutter with respect to `the work piece will then be again indicated by the arrow 45a, and the cutter will continue and complete the surface |69 and will continue over the surface |10.

By the present construction, it is apparent that by arranging the two cylinders 38 and 45 at angles to each other `andat angles 'to the direction of movement of the carriage, it is possible to negotiate the entire surface of the work piece 29 corresponding to the surface of the template 35 throughout continuous feedmovement of the carriage 2|, it being necessary only that there be an operator to switch the changeover valve from one position to another, thereby changing the control from one cylinder to the other at the proper time.

It is quite apparent also that there is no great necessity for quickly changing over from one cylinder to the other, as above explained. For instance, the changeover valve may be changed at any time while the cutter is negotiating the surface |65, for example.

In the reproduction of under-cut surfaces from a template similarly under-cut, the changeover Valve may be so arranged that a plus displacement of the tracer would cause the cutter to move downwardly as viewed in Fig. 2. This would be the movement required of the cutting tool in cutting a male part. Now,.in negotiating an under-cut or female part, the changeover valve would be turned to a position degrees from its initial position, with the result that the cutter would move in the opposite direction with the same type of positive placement of the tracer to thereby reproduce the female part.

As above described in detail, the switching of the changeover valve 180 degrees from one position to another merely reverses the direction effect caused by the tracer control valve with respect to one particular cylinder. It will be remembered that changing over 180 degrees turn, that the cylinder controlled is unchanged and further that only one cylinder is ever underI tracer control at one time.

It is quite clear, then, that the tracer construction set out in Fig. 9 is intended to control the operation of the cylinders 38 and 45 one at a time with said tracer being adapted to control direction of movement of the respective cylinders as well as the speed of movement thereof. As to which cylinder will be controlled by the tracer. this depends entirely upon the manual operation of the changeover valve. and the time of operation of this cylinder is controlled by the tracer.

As viewed in Fig. 8, the changeover Valve housing |23 is secured to the outer end of the hydraulic cylinder 38, movable therewith, said changeover valve being secured thereto at the point |10. u

Referring now to Fig. 6, there is a drain conduit 9| from the hydraulic unit |26, which as above described is connected with the drain pipe 96 and the tracer valve housing |06. As shown in Fig. 6, the drain pipe 9| also continues to the lower end of the changeover valve housing |23 for also conducting away any seepage `whichcollects within the lower end thereof. 

